1. Field of the Invention
The present invention relates to a printed-board conveying apparatus for. conveying a printed board such as a printed wiring board or a printed circuit board and particularly to such an a printed-board conveying apparatus which includes two belt conveyors which are juxtaposed with each other, i.e., are arranged in parallel with each other.
2. Discussion of Related Art
There is known a printed-board conveying apparatus which is employed by, e.g., an electric-component (EC) mounting system which mounts electric components (ECs) on a printed wiring board and thereby produces a printed circuit board. The EC mounting system includes, in addition to the printed-board conveying apparatus, a supporting device which positions and supports the printed wiring board conveyed by the printed-board conveying device; a supplying device which supplies ECs of different sorts; and a mounting device which receives the ECs from the supplying device and mounts the ECs on the printed wiring board supported by the supporting device. The printed-board conveying apparatus includes two belt conveyors.
In the EC mounting system, the mounting device mounts the ECs on the printed wiring board which has been carried in by the printed-board conveying apparatus and is supported by the supporting device. The printed wiring board on which the mounting of ECs has been completed, i.e., a completed, printed circuit board or a half-completed, printed wiring board is carried out by the conveying apparatus. After the current board is carried out and before the next board is carried in, the mounting device cannot mount any ECs, if the conveying apparatus has a single belt conveyor only. This leads to lowering the efficiency of production of printed circuit boards. Hence, the present conveying apparatus employs two belt conveyors which are arranged in parallel, so that while one of the two conveyors carries in and out printed wiring boards, the mounting device can mount ECs on a printed wiring board which is supported by a supporting device corresponding to the other conveyor. Thus, the present EC mounting system can continuously mount ECs on printed wiring boards, and thereby improve the efficiency of mounting of ECs.
However, in the case where the above-described EC mounting system mounts ECs on printed wiring boards of a large size, the printed-board conveying apparatus needs to employ two belt conveyors each of which has a large width and which are arranged in parallel. This needs to increase the size of the conveying apparatus and accordingly the size of the EC mounting system, which results in needing a large footprint. On the other hand, it is not so often for the EC mounting system to mount ECs on large-size printed boards. Thus, it is not desirable that the EC mounting system increase its own size or need a large footprint. These problems will occur to not only the EC mounting system but also an operation performing system which performs a prescribed operation relating to a printed board, such as an adhesive applying system which applies an adhesive to a printed board so that ECs are adhered to the board with the adhesive, or an inspecting system which inspects a completed, printed circuit board or a half-completed, printed wiring board.
The present invention provides a printed-board conveying apparatus and an operation performing system which have one or more of the following technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (12). Any technical feature that includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to the latter feature. However, the following technical features and the appropriate combinations thereof are just examples to which the present invention is by no means limited. In addition, in the case where one technical feature recites a plurality of items, it is not essentially required that all of those items be simultaneously employed. That is, it is possible to select and employ only a portion (one, two, . . . , but not all) of those items.
(1) According to a first feature of the present invention, there is provided a printed-board conveying apparatus comprising a first belt conveyor including a first stationary guide rail, a first movable guide rail, and two first belts which are circulated while being guided by the two first guide rails, respectively, and which support opposite end portions of a first printed board, respectively, and cooperate with each other to convey the first printed board; and a second belt conveyor which is arranged in parallel with the first belt conveyor and which includes a second stationary guide rail, a second movable guide rail, and two second belts which are circulated while being guided by the two second guide rails, respectively, and which support opposite end portions of a second printed board, respectively, and cooperate with each other to convey the second printed board, the first stationary and movable guide rails and the second stationary and movable guide rails extending parallel to one another in a first direction, such that the first and second stationary guide rails are provided outside the first and second movable guide rails, respectively, each of the first and second movable guide rails being movable toward, and away from, a corresponding one of the first and second stationary guide rails, so as to change a width of a corresponding one of the first and second belt conveyors, at least one of the first and second movable guide rails being movable, over a middle position between the first and second stationary guide rails, toward one of the first and second stationary guide rails that does not correspond to the one movable guide rail, so as to increase a width of one of the first and second belt conveyors that corresponds to the one movable guide rail.
In the case where the present printed-board conveying apparatus conveys printed boards of a small size, both of the respective widths of the two belt conveyors can be adapted to the small-size printed boards, so that while one of the two conveyors is stopped, the other conveyor can be operated to convey a small-size printed board. Therefore, if the present conveying apparatus is employed in an operation performing system which performs a certain operation relating to a printed board, as described later, one of the two belt conveyors can be stopped so that the operation is performed for the printed board which has been carried in by the one belt conveyor, and the other belt conveyor can be operated so that the printed board for which the operation has been completed is carried out and the next board is carried in. Thus, the present conveying apparatus can improve the operation efficiency of the operation performing system. That is, the present conveying apparatus can convey printed boards of a large size, without needing to be larger in size.
(2) According to a second feature of the present invention that includes the first feature (1), the printed-board conveying apparatus further comprises a first width-changing device which changes the respective widths of the first and second belt conveyors such that the respective widths of the two belt conveyors are equal to each other.
The two belt conveyors may have different widths and alternately convey printed boards of different sorts, respectively. However, in many cases, it is required that the two belt conveyors have a same width and alternately convey printed boards of a same sort. To this end, the first width-changing device is needed. The first width-changing device may include two individual width-changing devices which change the respective widths of the two belt conveyors. However, it is preferred that the first width-changing device include a synchronous width-changing device according to the third feature (3) described below.
(3) According to a third feature of the present invention that includes the second feature (2), the first width changing device comprises a synchronous width-changing device which moves the first and second movable guide rails, in synchronism with each other, such that a distance between the first stationary and movable guide rails and a distance between the second stationary and movable guide rails are kept equal to each other, and thereby changes the respective widths of the first and second belt conveyors, in synchronism with each other.
The synchronous width-changing device may be one which includes two individual width-changing devices which change the respective widths of the two belt conveyors and a control device which operates respective drive sources (e.g., electric motors) of the two individual width-changing devices, in synchronism with each other, or alternatively may be one according to the sixth feature (6) described below.
(4) According to a fourth feature of the present invention that includes any one of the first to third features (1) to (3), the printed-board conveying apparatus further comprises a width-changing device which changes at least one of the respective widths of the first and second belt conveyors such that one of the respective widths of the two belt conveyors is greater than the other of the respective widths of the two belt conveyors.
This width-changing device may be one which include two individual width-changing devices which change the respective widths of the two belt conveyors. However, it is preferred that the width-changing device have the construction according to any one of the fifth to seventh features (6) to (8) described below.
(5) According to a fifth feature of the present invention that includes the third feature (3), the printed-board conveying apparatus further comprises a second width-changing device which changes at least one of the respective widths of the first and second belt conveyors such that one of the respective widths of the two belt conveyors is greater than the other of the respective widths of the two belt conveyors.
(6) According to a sixth feature of the present invention that includes the fifth feature (5), the second width-changing device comprises an asynchronous width-changing device which moves at least one of the first and second movable guide rails, in asynchronism with the other of the first and second movable guide rails.
When the synchronous width-changing device is operated, the respective widths of the two belt conveyors can be changed while the two widths are kept equal to each other. On the other hand, when the asynchronous width-changing device is operated, the width of one of the two belt conveyors can be changed while the width of the other belt conveyor is kept unchanged.
(7) According to a seventh feature of the present invention that includes the sixth feature (6), the synchronous width-changing device comprises two individual width-changing devices which change the respective widths of the first and second belt conveyors; and a connecting and disconnecting device which is selectively placeable in a connecting state thereof in which the connecting and disconnecting device connects the two individual width-changing devices to each other and in a disconnecting state thereof in which the connecting and disconnecting device disconnects the two individual width-changing devices from each other, and which is currently placed in the connecting state, and the asynchronous width-changing device comprises at least one of the two individual width-changing devices and the connecting and disconnecting device which is currently placed in the disconnecting state.
According to this feature, both the synchronous and asynchronous width-changing devices enjoy a simple construction.
(8) According to an eighth feature of the present invention that includes the seventh feature (7), each of the two individual width-changing devices comprises at least two feed screws each of which extends in a second direction perpendicular to the first direction, is rotatable about an axis line thereof, and is not movable in a direction parallel to the axis line; at least two nuts which are fixed to a corresponding one of the first and second movable guide rails; and a rotation transmitting device which includes at least two rotatable members each of which transmits rotation to a corresponding one of the at least two feed screws such that the two feed screws are rotated in synchronism with each other, the connecting and disconnecting device comprises a clutch which is provided between the two rotatable members of one of the two individual width-changing devices and the two rotatable members of the other individual width-changing device and which is selectively placeable in the connecting and disconnecting states, and the asynchronous width-changing device comprises a clutch control device which places the clutch in the disconnecting state.
According to this feature, both the synchronous and asynchronous width-changing devices enjoy a simple construction.
(9) According to a ninth feature of the present invention that includes the seventh or eighth feature (7) or (8), the asynchronous width-changing device comprises an automatic width-change control device which first places the connecting and disconnecting device in the connecting state and operates the synchronous width-changing device to decrease the respective widths of the first and second belt conveyors and, then, places the connecting and disconnecting device in the disconnecting state and operates the one of the two individual width-changing devices to increase the width of a corresponding one of the two belt conveyors.
The synchronous width-changing device may comprise an automatic width-change control device which automatically places the connecting and disconnecting device in the connecting state and operates the two individual width-changing devices to change the respective widths of the first and second belt conveyors. In this case, both the synchronous width-changing device and the asynchronous width-changing device can automatically and easily operate for changing both or one of the widths of the two belt conveyors.
(10) According to a tenth feature of the present invention, there is provided a system for performing a prescribed operation, comprising a printed-board conveying apparatus according to any one of the first to ninth features (1) to (9); a supporting device which positions and supports each of the first and second printed boards conveyed by the printed-board conveying apparatus; and an operation performing device which performs a prescribed operation relating to the each printed board supported by the supporting device.
(11) According to an eleventh feature of the present invention that includes the tenth feature (10), the operation performing system further comprises a supplying device which supplies a plurality of electric components, and the operation performing device comprises a mounting device which receives the electric components from the supplying device and mounts the electric components on the each printed board supported by the supporting device.
(12) According to a twelfth feature of the present invention that includes the eleventh feature (11), the supporting device comprises two individual supporting devices which support the first and second printed boards, respectively, which have been conveyed by the first and second belt conveyors, respectively, and the mounting device comprises at least two mounting heads; and a mounting control device which is selectively operable in a first control mode in which the mounting control device controls the two mounting heads to cooperate with each other to receive the electric components from the supplying device and mount the electric components on each of the first and printed boards which are supported by the two individual supporting devices, respectively, and in a second control mode in which the mounting control device controls the two mounting heads to cooperate with each other to receive the electric components from the supplying device and mount the electric components on one of the first and printed boards which has been conveyed by the one of the first and second belt conveyors that has the increased width and which is supported by one of the two individual supporting devices that corresponds to the one belt conveyor.